To determine whether Hydroxyurea enhances long term viral suppression in subjects receiving IDV, ddI and d4T and whether switching from IDV, ZDV (or ddI) and 3TC to IDV, ddI and d4T enhances long-term viral suppression and thirdly, whether switching from IDV, ZDV (or ddI) and 3TC to IDV, d4T, ddI and hydroxyurea enhances long term viral suppression.